Man pages matching name xcb_composite_unredirect_subwindows in section 3:

xcb_composite_unredirect_subwindows.3.en	debian 10 / libxcb-doc
xcb_composite_unredirect_subwindows.3.en	debian 11 / libxcb-doc
xcb_composite_unredirect_subwindows.3.en	debian 12 / libxcb-doc